1. Field of the Invention
The present invention relates to an apparatus for reversing a lead frame, and more particularly to an apparatus for reversing upper and lower surfaces of a lead frame which passes through a silver plating process in a lead frame manufacturing method.
2. Description of the Related Art
A lead frame has a one-frame structure supporting a semiconductor chip. As shown in FIG. 1, the lead frame functions as a contacting port which electrically connects the chip with external terminals and as a path through which heat generated in the chip is radiated outside.
To make the lead frame 1, there are needed, in brief, a press process for stamping an original material, a silver-plating process for treating a wire bonding portion and a taping process.
In particular, upper and lower surfaces of the lead frame 1 are reversed in order to prevent damage caused when the lower surface plated after the silver-plating process is in contact with conveying rollers. In the prior art, as shown in FIG. 2, the lead frame 1 carried on rollers 2 are attached by absorption to a carrying unit 4 and transferred to a reversing robot 3. The reversing robot 3 then rotates the lead frame 1 at 180xc2x0, for the purpose of the reversing.
However, this conventional method shows many problems that too many costs are required to configure the reversing robot 3, a power is needed to drive the reversing robot 3, and there arise frequent malfunctions since the reversing robot 3 needs high accuracy.
The present invention is designed to overcome such problems of the prior art, and an objective of the invention is to provide an apparatus for reversing a lead frame which reverses upper and lower surfaces of the lead frame without any power.
Another objective of the invention is to provide an apparatus for reversing a lead frame which has a simple structure to minimize malfunctions and costs.
In order to accomplish the above objective, the present invention provides an apparatus for reversing a lead frame, which reverses upper and lower surfaces of the lead frame passing through a silver plating process, which includes at least one guide rail having a curved portion for guiding the lead frame to be fallen down and reversed along an arc of the curved portion, and a conveying roller provided under the guide rail to horizontally convey the fallen lead frame.
Preferably, the guide rail includes an inner wire having an upper portion and an inner central portion, which are in an arc shape ranging from an upper area to a central area, outer central portions connected to the inner central portion and extended as much as 90xc2x0 arc with a predetermined space in the central area, and a lower portion in a straight shape extended downward in connection with the outer central portion, and an outer wire having an upper portion in a straight shape extended downward with being spaced apart from the upper portion of the inner wire, a central portion extended as much as 90xc2x0 arc in connection with the upper portion, and a lower portion extended downward in a straight shape in connection with the central portion.
Alternatively, the guide rail may also include an inner wire having an upper portion of an arc shape, a central portion of a xe2x80x98xe2x80x99 shape having a first horizontal portion, a vertical portion and a second horizontal portion, and a lower portion in a straight shape extended downward in connection with the central portion, and an outer wire having an upper portion in a straight shape extended downward with being spaced apart from the upper portion of the inner wire, a central portion extended as much as 90xc2x0 arc in connection with the upper portion, and a lower portion extended downward in a straight shape in connection with the central portion.
In this case, the apparatus for reversing a lead frame may also include a cushion to be installed to one side of the central portion of the inner wire to stop and arrange the naturally-fallen lead frame with absorbing shock.
In both cases, a vertical central line of the inner wire is preferably offset from an initial drop position of the lead frame.
In addition, it is also preferable that there are provided a plurality of guide rails, and upper ends of the inner wires and upper ends of the outer wires are connected to each other through a connection rod.
The apparatus for reversing a lead frame may also include a base for supporting the guide rail, and a combining member for combining the guide rail to the base so that the height of the guide rail is adjustable.
In another case, it is also possible that the apparatus for reversing a lead frame includes a base for supporting the guide rail, and the guide rail is integrated with the base.
In any case, the bases can be installed under each guide rail in parallel to a longitudinal direction of the conveying rollers, and ends of the bases can be connected to each other through a connection bar.